Compositions comprising polyacrylonitrile and beta, beta&#39;-iminodipropionitrile



Patented July 3, 1951 'UNITED l CoMPosrrIoNs coMPRIsING POLY-V AcnYLoNrrRILE AND ,p'rMINoDI PROPIONITRILE William C. Schneider, Stamford, and John J.

Padbury, Springdale, Conn., assignors to American Cyanamid Company, New York, N. Y., a

corporation of Maine Application September 19, 1950, Serial No. 185,628

This invention relates to new and useful compositions of matter and more particularly to compositions comprising an acrylonitrile polymerization product and ,'iminodipropionitrile, HN(CH2CH2CN) 2. 'I'he compositions of this invention in which the aforementioned dipropionitrile is employed primarily as a solvent for the acrylonitrile polymerization product. in which case it constitutes a major proportion (more than 50%), e. g.. from 55 to 95% or more, by weight of the composition, are particularly useful in the production of shaped articles therefrom, e. g'., films, fllamentsthreads, rods, tubes and the like. ,'iminodipropionitrile also may be used primarily as a plasticizer for an acrylonitrile polymerization product, in which case it usually constitutes a minor proportion (less than 50%), e. g., from 0.5 to 45%, generally from i to 35 or 40% by weight of the composition.

Various methods of producing filaments, films -and other shaped articles from polyacrylonitrile (polymeric acrylonitrile) and from copolymers or interpolymers of a major proportion of acrylonitrile and a minor proportion of another Acither shaped bodies therefrom. Also, in Rein U. S.A Patent No. 2,140,921 it is proposed that various polyvinyl compounds including polyacrylonitrile and copolymers of acrylonitrile with an- Y other vinyl compound be dissolved in concentrated aqueous solutions of inorganic (metal) salts, e. g., the chlorides, bromides, iodides, thiocyanates, perchlorates and nitrates, and that the resulting solutions be usedV in` the manufacture of threads, films, etc.

The present invention is based on our discovery that polymers and copolymers of acrylonitrile, more particularly polymeric acrylonitrile and thermoplastic copolymers of acrylonitrile, specifically such copolymers containing in their molecules an average of at least 85% by weight of combined acrylonitrile, e. g., copolymers of, by weight, from 85 to 99.5% of acrylonitrile and another monomer such, for instance, as vinyl acetate, methyl acrylate, ethyl acrylate, acrylamide, etc., are compatible with .p'-iminodipro 9 Claims. (Cl. 26o-32.4)

pionitrile and that this dipropionitrile is capable of dissolving theacrylonitrile polymerizaton product to yeld solutions which are suitable for use in -making monothreads, yarns, bars, lms, etc., therefrom. The invention is based on our further discovery that the aforementioned dipropionitrile is able effectively tov plasticize acrylonitrile polymerization products, so that the latter more easily can be shaped, as by extrusion or molding, into useful articles of manufacture. The dipropionitrile employed in practicing our invention may be used either as a fugitive or temporary plasticizer, that is, a plasticizer which subsequently is removed from the polymerization product, or as a permanent plastcizer which is permitted to remain in the shaped polymer or copolymer.

The present invention is based on our additional discovery that ,-iminodipropionitrile plasticized acrylonitrile polymerization products containing in the molecules thereof an average of at least 85% by weight of combined acrylonitrile have an extremely high dielectric constant with a relatively low dielectric loss, as a consequence of which they are eminently suitable for use in the construction of capacitors. In electrical applications of the compositions of our invention, the amount of ,'iminodipropionitrile plasticizer which is present in the acrylonitrile polymerization product advantageously is from about 5% (preferably at least about 7%) to about 40%, more particularly from about 10% to about l%, e. g., about 20 or 25%, by weight of the plasticized acrylonitrile polymerization product. If the plasticizerconstitutes less than about 5-7% by weight of the plasticized product, the improvement in electrical properties over the unplasticized acrylonitrile polymerization product is relatively small, usually being too small to be of practical significance. On the other hand, when the plasticizer constitutes more than about 40% by weight of the plasticized product. the electrical resistance of the dielectric is generally too low for use of the material as a condenser dielectric. From this it will be seen that, in elec- Y and multiiilaments,

'iminodipropionitri1e, with a smaller amount of aminoproplonitrile. iminodipropionltrile is a colorless liquid having a boiling point of 140 C. under a pressure of 1 mm. of mercury, and a boiling point of 173 C. under ,10 mm. mercury pressure. It is miscible with a wide variety of other liquids, for example, water, ethanol, ethylene glycol, diethylene glycol, acetone, chloroform and benzene. It does not cause decomposition of, nor appear to react chemically with, an acrylonitrile polymerization product. Furthermore, it can be partially or substantially completely removed from films, threads, or other shaped bodies which are produced from a solution of polymeric or copolymeric acrylonitrile in the said dipropionitrile. It appears that ,iminodi propionitrile is completely thermally stable at temperatures up to at least 150 C. and that it is approximately five times as stable under heat as ,'oxydipropionitrile, which very slightly decomposes when heated for hours at 175 C. The solutions of the acrylonitrile polymerization product in iminodipropionitrile also are stable over a long period of time providing the solution is maintained above its gelation temperature and below the decomposition temperature of the dipropionitrile.

Polymeric acrylonitrile and acrylonitrile copolymers (thermoplastic acrylonitrile copolymers) containing in the polymer molecules an average of at least 85% by weight of combined acrylonitrile are employed in carrying the present invention into effect. These polymers and copolymers are prepared by methods now well known to-those skilled in the art. In some cases the polymerization rates of the individual monomers in a polymerizable mixture may-be dilerent, with the result that the proportions of the components in the final copolymer are different from the proportions thereof in the mixture of monomers which is polymerized. The proportions of monomers in the polymerizable mixture therefore preferably are adjusted, in practicing the present invention, so that the final copolymer contains in the molecules thereof an average of at least 85% by weight of combined acrylonitrile. The expression polymerization product containing in the polymer molecules an average of at least 85%,by weight of combined acrylonitrile, as used herein and in the appended claims, means a-polymerization product (polymer, copolymer or interpolymer or mixtures thereof) containing in their molecules an average of at least 85% by weight of the acrylonitrile unit, which is considered tobe present in the individual polymer molecule as the group or, otherwise stated, at least 85% by weight of the reactant substance converted into and forming the polymerization product is acrylonitrile.

Illustrative examples of monomers which may be copolymerized with acrylonitrile to yield a polymerization product (copolymer or interpolyare disclosed, for example, in Pfann and Kropa copending application Serial No. 738,736, led

April 1, 1947; allyl, methallyl and other unsaturated monohydric alcohol esters of monobasic acids, e. g., allyl and methallyl acetates. laurates, cyanides, etc.; acrylic and alkacrylic acids `(e. g., methacrylic.' ethacrylic, etc.) and esters and amides of such acids (e. g., methyl, ethyl, propyl, butyl, etc., acrylates and methacrylates, acrylamide, methacrylamide, N methyl, ethyl. propyl, butyl. etc.. acrylamides and methacrylamides, etc.); methacrylonitrile, eti-.acrylonitrile and other hydrocarbon-substituted acrylonitriles; unsaturated aliphatic hydrocarbons containing a single CH2=C grouping, e. g., isobutylene, etc.; and numerous other vinyl, acrylic and other compounds containing a single CH2=C grouping which are copolymerizable with acrylonitrile to yield thermoplastic copolymers. Alkyl esters of alpha,betaunsaturated polycarboxylic acids also may be copolymerized with acrylonitrile to form copolymers which are useful in practicing the present invention, e. g., the dimethyl, ethyl, propyl, -butyl, etc., esters of maleic, fumarie, citraconic, etc., acids.

The proportions of monomers in the polymerizable mixture may be varied as desired or as may be required in order to obtain a polymerization product containing in the polymer molecules an average of at least by weight of combined acrylonitrile. Thus, when the polymerization rate of the monomers present in the polymerizable mixture is substantially the same, the proportions may be, for example, from, by weight, about 85% to about 99% of acrylonitrile to form about 15% to about 1% of the other comonomer. When the polymerizable mixture contains, in addition to the acrylonitrile, a monomer such, for example, as vinyl chloride, allyl alcohol, etc., which polymerizes at a rate different from that of acrylonitrile, then it may be necessary to subject to polymerization conditions a mixture in which the acrylonitrile constitutes as little as, for

instance, 50 or 60% by weight thereof in order tol obtain a polymerization product containing in thc copolymer molecules an average of at least 85 by weight of acrylonitrile.

Any suitable method of polymerizing thel monomeric arcylonitrile or mixture of monomers may be employed. One suitable method comprises polymerizing the monomer or mixture of monomers in an aqueous emulsion using a suitable polymerization catalyst, e. g., ammonium persulfate. Other polymerization methods, however, also may be used, e. g., methods such as those described in Bauer et al. U. S. Patent No. 2,160,054, Jacobson U. S. Patent No. 2,436,926, and others. The polymeric and copolymeric acrylonitriles used in practicing our invention may be of any suitable molecular weight, but ordinarily the molecular weight (average molecular Weight) is within the range of 15,000 to 300,000 or higher, and advantageously is of the order of 35,000 or 40,000 to 140,000 or 150,000, as calculated from viscosity measurements using the Staudinger equation (reference: U. S. Patent No. 2,404,713).

'I'he dissolution of the acrylonitrile polymerization product in the ,-iminodipropionitri1e is accelerated by using a polymer or copolymer which is in iinely divided state, e. g., one which,

if not in nely divided state as originally formed, has been ground so that all or substantially all of it will pass through a U. S. Standard Sieve Series No. 55 screen. It also is usually desirable v to agitate the mass, as by mechanical stirring, while dissolving the polymerization product in the solvent. To avoid or vminimize discoloration ofthe -polymeric or copolymeric larcylonitrile, 'it is generally advantageous to employ the lowest possible temperature in effecting dissolution or widely, depending mainly upon the particularv use for which the composition is intended. If the dipropionitrile is employed primarily as a solvent for the polymer or copolymer so as to obtain a film, lament, thread, yarn, rod, tube or other shaped article from which al1 or substantially all of the solvent subsequently is removed, then the acrylonitrile polymerization product usually constitutes at least 4 or 5% but'less than 50%, e. g., from 5 to about 20 cr 25%, by weight of the composition. If the solution is to be used in the spinning of filaments (monoor multiiilaments) or the casting of films, it is generally preferred that the polymer cr copolymer constitute at least 7 or 8% e. g., from 10 to 15 or 20%, by weight of the composition.

The aforementioned ranges of proportions are mentioned as indicative of proportions that may be employed in forming solutions of the polymerization product, and our invention obviously is not limited to the use of only such proportions. Especially in spinning and casting applications of the compositions, the important factor is that the proportions besuch that the viscosity of the composition at the operating temperature is within a workable range. Satisfactory viscosities at the usual operating temperatures generally prevail when the polymer or copolymer constitutes between about 5% and about 10% by Weight of the composition, but this also is dependent upon the average molecular yweight of the polymerization product which may range, for example, from 15,000 or 20,000 up to 150,000 or 200,000, or even as high as 250,000 or 300,000 or more, as determined from viscosity measurements and calculations by the Staudinger equation.

Because the use of the higher amounts of solvent renders spinning operations more costly and difficult due to the trouble often encountered in rapidly removing large amounts of solvent from the solution and due to the cost of such removal. even though the solvent be recovered, it is preferable to use a polymerization product having a molecular weight such that a maximum amount of the polymer or copolymer, consistent with the viscosity of the solution at the operating temperature, can be dissolved in the ,/3'imino dipropionitrile. Byy using acrylonitrile polymerization products having an average molecular weight (Staudinger method) within the range of 35,000 or 40,000 up to 150,000 or 160,000, it is possible to obtain solutions containing, for instance, from 5 to 10% or more by weight thereof of the polymer or copolymer, and having suitable viscosities for use at operating temperatures of the order of 130 C. to 180 C. or higher.

The solutions described above may be used in the production of various fabricated structures such. for example, as films, filaments, bars, rods, tubes, etc., in accordance with general techniques and using apparatus now generally known to those skilled in the art, the detailed operating conditions being suitably modied where required.

In one method of making extruded articlessuch, for example, as filaments, etc., the solutionv (advantageously heated to, for instance, 100 to 180 C. and in all cases above its gelationtemperature) is extruded through a spinneret or die into a liquid coagulating bath which will coagulate thepolymerization product in the-spinning solution. The liquid into which the spinning solution is extruded is one which is miscible with',iminodipropionitrile and which,

as a result of extracting the solvent, is capable of coagulating the polymerization product. Any liquid which is thus capable of coagulating the polymer or copolymer may be employed, but preferably the liquid coagulant is one which has no harmful effect upon the polymerization product. Examples of liquid coagulants that can be used at room temperature are water, ethanol, acetone, chloroform, benzene, ethylene glycol, diethylene glycol and others. The higher boiling solvents. e. g., Water, ethylene glycol, diethylene glycol, etc., also can be used at higher temperatures to coagulate the polymerization product from its solution in ,iminodipropionitrile.

It will be understood, of course, by those skilled in the art that the temperature of the liquid coagulating or precipitating bath should be such as to dissolve the solvent from the extruded mass most rapidly and effectively. The length of travel of the shaped article through the bath may be varied as desired or as conditions may require. but in all cases should be suiciently long to eiect solidiflcation of the polymerization product and to extract from the extruded mass all of the solvent, or, if desired, only a part of it, leaving vthe remainder, e. g., from 0.5 or 1% to 15 or 20% or more, by weight of the whole, in the extruded mass so that it may function as a plasticizer for the polymerization product. One or more sheaves or rolls may be positioned in the bath so as to guide the filament during its formation and to keep it under tension thereafter.

The spun filament or other extruded article is preferably treated in, or after leaving, the coagulating bath in order to orient the molecules and thereby to increase the tensile strength and otherwise to improve the properties of the spun material. Orientation may be effected by stretching the thread or strand at any suitable stage of the spinning operation, but preferably while the spun filament or thread still contains at least some of the solvent. Stretching may be accomplished by passing the thread or yarn between two or more positively driven rollers or godets, the peripheral speeds of which are adjusted so that. the thread is stretched to the desired degree.

The amount of stretch that is applied to the filament or strand may be varied Widely, but in all cases should be sufficient to cause at least appreciable orientation of the molecules and an improvement in the properties of the material undergoing treatment. The amount of tension to which the strand is subjected obviously should not be so great as to cause it to break. Depending, for example, upon the type or kind of material being stretched and the particular properties desired in the finished product, the amount of stretch may vary, for instance, from preferably from 200 or 300%, up to 1000% or more of the original length of the filament or strand. The stretch may be applied gradually by passing the thread over a plurality of godets it may be collected in a centrifugal pot. whereby twist advantageously is applied to the thread. Alternatively, the stretched thread may be led over a thread-storage device on which it may be treated with a suitable solvent to remove all or part ofA the coagulant and/or ,iminodi propionitrile, after which it may be continuously dried, oiled and taken up on a twisting device such, for instance, as a ring twisting spindle.

The extruded filament or thread may be given part or all of its total stretch in a liquid medium such as that which constitutes the coagulating bath, or in any other suitable medium, and at a suitable temperature. Thus, the stretch may be applied While the strand is being passed through a gaseous medium, e. g.. air, nitrogen, ue gases, etc., or through a liquid medium, e. g.,

water, or such media as are employed for coagulating the polymerization product. To obviate or minimize discoloration of the polymerization product. the temperature of the medium in which the polymer or copolymer is stretched and the` rate of travel of the strand through the medium should be so acusted that overheating of the strand does not occur. Ordinarily the temperature of the medium in which stretching is elected is below 200 C., e. g., at 110 to 140 C.

The highly stretched product is strong, tough and pliable, and shows a high degree of :orientation along the fiber axis by X-ray diffraction.

The solvent solutions of the acrylonitrile polymerization product also can be cast in the form oi' lms. For instance, the hot, liquid composition may be cast upon a revolving drum which is partly immersed in a coagulating bath, such as mentioned hereinbefore, and which will serve to deposit the polymerization product as a thin illrn on the drum as it passes through the bath. The resulting fllm may be stretched, if desired,'length wise and crosswise by suitable apparatus to improve its properties.

As indicated hereinbefore, the spinning operation can be so conducted as to leave some of the ,iminodipropionitrile in the polymerization product as a plasticizer therefor. Other means, however, also can be employed for plasticizing a polymer or copolymer of acrylonitrile with iminodipropionitrile. For example, a water-I swollen filament or thread of polymeric or copolymeric acrylonitrile which has been produced as described in Cresswell copending application Serial No. 772,200, filed September 4, 1947, can be" treated, as by immersion, with the said dipropionitrile. Or, ,iminodipropionitrile can be dissolved in a solvent, e. g., water, ethanol and others such as previously have been mentioned, and this solution then can be usedin treating the waterswollen, stretched or unstretched thread.

Compositions comprising, by weight, from about 5 or 10% to about 35 or 40% of ,'mino dipropionitrile and the remainder an acrylonitrile polymerization product containing in the molecules thereof an average of at least 85% by weight of combined acrylonitrile are especially suitable for use as a dielectric or as a component of a dielectric in an electric capacitor, as is more fully described in the copending application of William C. Schneider, Serial No. 180,370, filed August 19, 1950, with particular reference to the use in electric capacitors of dielectrics comprising such an acrylonitrile polymerization product with a different plasticizer. The ,iminodipropionitrile plasticized acrylonitrile polymerization product also can be combined with paper, fabrics compris-v ing fibers oi' an acrylonitrile polymerization product, and other dielectrics of the kind and in the manner disclosed, for example, in the aforementioned Schneider application.

Figs. 1 and 2 of the accompanying drawing I show, respectively, the dissipation factor and the dielectric constant of Amolded compositions produced by molding (in the form of a disk 1A; inch thick) a homogeneous mixture of, by weight, polyacrylonitrile (homopolymeric acrylonitrile) having a molecular weight of about 70,000 as determined from a viscosity measurement using the Staudinger equation, and 20% ,imlnodipro pionitrile at about C. under a pressure of about 5400 pounds per square inch. The graphs show the dielectric constant and the dissipation factor of the composition when these properties were determined at 28 C. and at different frequencies.

The broad statement has been made in'the patent literature that compounds which are fusible without decomposition and which contain at least two cyanomethylene groups will dissolve polyacrylonitrile and copolymers of acrylonitrile in which at least 85% by weight of the polymer is acrylonitrile. The following examples show that not all compounds which are fusible without decomposition and which contain at least two cyanomethylene groups-are capable of dissolving such acrylonitrile polymerization products:

Example 1 Five-tenths of a gram of powdered polyacrylo- `nitri1e was added to 5 grams of N-ethyl-N-cyano- Example 2 Five grams of N-methyl-N-cyanomethylaminoacetonitrile (a liquid at room temperature) was added to 0.5 gram of polyacrylonitrile and the mixture was heated slowly with stirring to 200 C. The polymer did not dissolve and on cooling was found to be unaffected, except for discoloration, by the N-methylN-cyanomethylaminoacetonitrile.

In order that those skilled in the art better may understand how the present invention can be carried into eil'ect, the following examples are given by way of illustration and not by way of limitation. 'All parts are by weight.

Example 3 A mixture of 0.5 part of polyacrylonitrile and 50 parts of ,iminodipropionitrile is heated to 180 C. in a vessel placed in a heated oil bath, at which temperature a clear solution results. The solution remains clear upon cooling to 25 C.

A clear solution is obtained by heating a mixture of 1 part of polyacrylonitrile and 10 parts of ,iminodipropionitrile to 180 C. Upon coolv ing, the solution becomesl cloudy at C. and is an opaque solid at 25 C.

Example 5 plasticized polyacrylonitrile has a Peakes ilow of 147 C., which is the temperature at which the material being tested will flow 1 inch in 2 minutes.

under a pressure of 2500 pounds per square inch. This composition can be molded into various shaped articles, e. g., disks, bars, etc., under heat and pressure, for instance at 150160 C. and under a pressure of from 4000 to 5400 pounds per square inch.

Example 6 Example 7 A filament or ber produced from ,'-imino dipropionitrile and polyacrylom'trile in the manner described under Example 6 and which contains a small amount of the order of 3% of residual 5,13'-iminodipropionitrile is stretched about 500% to orient the molecules along the fiber axis, yielding a plasticized oriented filament of polyacrylonitrile.

Example 8 A mixture of 95 parts of ,iminodipropioni trile and parts of a finely powdered copolymer, produced by copolymerization in aqueous solution of 95 parts acrylonitrile and 5 parts methyl acrylate, is heated with stirring to 135-140 C.,

yielding a clear solution. Upon cooling to room temperature a soft, translucent gel is obtained.

Example 9 Same as in Example 8 with the exception that the copolymer is one produced by copolymerization in aqueous solution of 90 parts acrylonitrile and 10 parts acrylamide, and the mixture of solvent and copolymer is heated to 135-l45 C. The resulting clear solution forms a soft, translucent gel upon cooling to room temperature.

Escample 10 Same as in Example 8 with the exception that the copolymer is one produced by copolymerization in aqueous solution of 90 parts acrylonitrile and 10 parts methyl methacrylate, and the mixture of solvent and copolymer is heated to 175- 185 C. A clear solution results. This solution also forms a soft, translucent gel when it is cooled to room temperature.

Example 11 A homogeneous mixture of 30 parts polyacrylonitrile (homopolymeric acrylonitrile) and 2O parts 139'-iminodipropionitrile is molded into a disk, 1/g-inch thick and 4 inches in diameter, at

about 155 C. under a pressure of about 5400 pounds per square inch. A sample disk (2 inches in diameter) is machined from the larger disk, and to it are attached tin-foil electrodes, 0.0005 inch thick, using a thin lm of petroleum jelly in making the attachments. The dielectric constant and dissipation factor of the sample are measured at 28 C. over a frequency range extending from 50 cycles per second to 5 megacycles -.Iminodpropio nitrile-plasticzed Unpldstlciztdf 015" Frequency m Polyacrylonitrile mty om n e Cycles per Second Dielectric Dissipation Dielectric Dissipation Constant Factor Constant Factor 50 8200 1. 05 4. 53 0. 053 100 6900 0. 99 4. 4l 0.052 500 2600 l. 53 4. l5 0. 045 1, 000 1182 2. 2l 4. 07 0. 042 5,000 209 3. 35 3. 90 0. 032 10,000 122 3. 05 3.84 0. 031 50, 000 i7. 4 1. 81 3. 72 0. 027 100, 000 31. 8 1.52 3. 68 0. 025 500, 000 16. 2 0. 85 3. 58 0. 025 1, 000, 000 13. 0 0. 73 3. 54 0.016 5, 000, 000 9. 2 0.32 3. 53 0. 012

It will be understood, of course, by those skilled in the art that our invention is not limited to the specific proportions of ingredients, operating conditions and procedures given in the above i1- lustrative examples. Likewise, polymerization products other than those given in the examples may be used. For instance, instead of the particular copolymers of acrylonitrile and methyl acrylate, acrylonitrile and acrylamide, and acrylonitrile and methyl methacrylate employed in the examples, we may use such copolymers in which the acrylonitrile is present in the copolymer molecules in other proportions Within the range of, for example, an average of 85% to 99% or more by Weight, or other copolymers of acrylonitrile and another monomer, numerous examples of which have been given hereinbefore, and in which the acrylonitrile constitutes at least 85% by weight of the copolymer molecule.

From the foregoing description it lwill be seen that the present invention provides compositions comprising an acrylonitrile polymerization product (polymer, copolymer or nterpolymer) and '-iminodipropionitrile either as a, plasticizer or as a solvent therefor. v

Instead of using '-iminodipropionitrile alone as a plasticizer or solvent for acrylonitrile polymerization products of the kind with which the present invention'is concerned, we can use the said dipropionitrile in combination with other known solvents or plasticizers for a polymer or copolymer of acrylonitrile, and in any proportions. For instance, as a solvent for the aforementioned acrylonitrile polymerization product, We can use a concentrated aqueous solution containing a mixture of ,iminodipro pionitrile and a water-soluble inorganic salt (or plurality of such salts), more particularly such a salt or salts which yield highly hydrated ions in yaqueous solution, e. g., the chlorides, bromides, thiocyanates, perchlorates and nitrates, which salts, aredisclosed, for example, in the aforementioned Rein Patent No. 2,140,921. More specic examples of such water-soluble inorganic salts are zinc chloride, calcium chloride, lithium bromide, cadmium bromide, cadmium iodide, sodium thiocyanate, zinc thiocyanate, aluminium perchlorate, calcium perchlorate, calcium nitrate, znc nitrate, etc. Examples of other salts that can be employed in combination with 8iminodipropionitrile in carrying the present invention into effect, more particularly in the form of an aqueous solution as a solvent for the hereindescribed polymers and copolymers of acrylonitrile, are guanidine thiocyanate, the mono- (lower alkyl) -substituted guanidine thiocyanates and the symmetrical and unsymmetrical di-(lower alkyl) -substituted guanidine thiocyanates, which salts are more fullyA described (including their l3. A composition as in claim 1 wherein the polymerization lproduct of (1) has an average -v molecular weiglit within the range oi'l 15.000 to use as solvents for acrylonitrile polymerization salts, of course, shouldl n ot be used when the.

composition vis to be employed as a dielectric.

The compositions of this invention can be shaped o r fabricated, as by extrusion, molding, casting, etc., into a wide variety of useful articles. Lubricants, anti-static. agents and other conventional modiilers of acrylonitrile polymerization products can be incorporated therein at any suitable stage of the operation. Other and more specic examples of modifiers that can be employed are given in the aforementioned Cresswell copending applications, as well as in the prior art patents hereinbefore acknowledged. Compositions containing, for example, from 3 to 50% by weight of '-iminodipropionitrile and the remainder an acrylonitrile polymer or copolymer of the kind described above can be molded under h eat andl pressure to provide a wide variety of shaped, `plasticized acrylonitrile polymerization products.

, Although not limited thereto, the compositions of this invention are particularly useful in the production of `filaments, threads, yarns, etc.,

which thereafter are woven into fabrics. and also as capacitor dielectrics and in other applications of dielectrics. Other uses include those given in the aforementioned patents.

The term lament as used generically herein and in one of the appended claims is intended to include within its meaning both monolaments and multilaments.

We claim:

l. A composition of matter comprising (Tl a polymerization product containing in the polymer molecules an average of at least 85% by weight of combined acrylonitrile and (2) p49- iminodipropionitrile.

2. A composition as in claim 1 wherein the polymerization product is homopolymeric acrylonitrile.

4. A composition as in claim vl wherein the polymerization product of (l) constitutes at least 5% by weight of the composition.

5. A composition adapted for the production of lms, illaments, threads, rods, tubes and the like comprising ,iminodipropionitrile having dissolved therein a, polymerization product containing in the polymer molecules an average oi at least 85% by weight oi.' combined acrylonitrile,

" said polymerization product constituting from about 5% to about 25%, byweight, of the total amount of polymerization product ,and iminodipropionitrile. v

6. A plasticized composition comprising a polymerization product containing, in the polymer.

molecules an average of-:at least by weight Vof combined acrylonitrile, said polymerization product being plasticized with a plasticizing amount not substantially exceeding 40% by weight of the composition .oi' a plasticizer comprising '-iminodipropionitrile.

7. A composition comprising a plasticized polymerization product containing in thepolymer molecules an average of at least 85% by weight of combined acrylonitrile, said polymerization product being plasticized with from about 1% to about 35% by weight of the whole of ,'im inodipropionitrile.

8. A composition as in claim 7 wherein vthe polymerization product is homopolymeric acrylonitrile.

9. A filament which shows orientation along the ber axis and which comprises a polymerization product containing in the polymer molecules an average of at least 85% by weight of acrylonitrile, said polymerization product being plasticized with from about 1% to about 20% by weight of the whole of p,'iminodipropioni trile.

WILLIAM C. JOHN' J. PADBURY.

No references cited.

Certificate of Correction Patent No. 2,559,172 July 3, 1951 WILLIAM C. SCHNEIDER ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 2, line 3, for yeld read yield; column 4, line 35, for form read from; line 49, and column 5, line 4, for arcylonitrile read acm/Zomtm'le; column 4-` line 75, for 55 read 50; column 5, line 28, after 8% insert a comma; column 8, line 59, for "-iminodipropionitrile read ,zmn0dz' propz'omt'z'le and that the said Letters Patent should be read as corrected above, so that e same may conform to the record of the case in the Patent Ofce Signed and sealed this 23rd day of October, A. D. 1951.

THOMAS F. MURPHY,

Assistant Oommz'sszoner of Patents. 

1. A COMPOSITION OF MATTER COMPRISING (1) A POLYMERIZATION PRODUCT CONTAINING IN THE POLYMER MOLECULES AN AVERAGE OF AT LEAST 85% BY WEIGHT OF COMBINED ACRYLONITRILE AND (2) B,B''IMINODIPROPIONTRILE. 